Telephone-exchange system



J. L. McQUARRIE AND C. L. GOODRUM.

TELEPHONE EXCHANGE SYSTEM.

mwucmon FILED AUGJ, 1919.

1,393,558, Patented Oct. 11, 1921.

2 SHEETS-SHEET I.

Jub. I

fI/ffl/ J. L. McQUARRIE AND C. L. GOODRUM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED A'um, 1919.

I hvenfors James 1. Ma 004ml? Char/e5 L. 6004mm UNITED STATES PATENT OFFICE.

JAMES L. MCQUARRIE, OF MONTCLAIR, NEW JERSEY, AND CHARLES L. GOODRUM,

OF NEW YORK, N. Y., ASSIGNORS T0 WESTERN ELECTRIC COMPANY INCORPO- RATED, OF NEW YORK, N. 'Y., A CORPORATION OF NEW YORK.

TELEIEHONE-EXGHAN GE SYSTEM.

Specification of Letters Patent.

Patented Oct. 11, 1921.

Application filed August 7, 1919. Serial No. 315,827.

To all whom it may concern:

Be it known that we, JAMES L. MCQUAR- run and CHARLES L. GooDRUM, citizens of the United States, residing at Montclair, in the county of Essex and State of New Jersey, and New York, in the county of New York and State of New York, respectively, have invented certain new and useful Improvemerits in TelephoneExchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improvements in telephone exchange systems and has particular reference to circuit arrangements for various switches therefor.

An object of the invention is to provide a controlling mechanism for selector switches which may be temporarily utilized for controlling any one of a plurality of switches and which is selected after one of the switches has been seized.

Another object is to control the operation of any one of a plurality of final selector or connector switches by a common mechanism which is associated with the switch to be operated after the same has been seized and which remains in association therewith for the duration of a call.

The inventive idea involved is capable of receiving a variety of expressions one of which, for the purpose of illustrating the invention, is shown in the accompanying drawings; but it is to be expressly understood that drawings are employed merely for the purpose of facilitating the description of the invention as a whole and not to define the limits thereof, reference being had to the appended claims for this purpose.

In the drawings, Figure 1 is a diagrammatic view of a selector switch and circuits employed in connection therewith; Fig. 2 is a similar view of a final selector or connector switch.

The systemof the present invention has been shown as including a selector switch A and a connector switch B, but it will be understood that the number of switches necessary in establishing a call may be increased to conform with the capacity of an exchange.

Briefly, a number of selector switches A are provided with a mechanism 0 associated with a multipled bank of stationary contacts and operated by stepping means responsive to an electrical condition applied to connect the incoming line with the seized switch. The operation of the switch is then controlled by a mechanism shown at the left of Fig. 1 which is common to a number of switches but unavailable to any other but the seized switch during the actual operation thereof. WVhen the switch has extended the calling line, mechanism 0 is restored to normal and together with said common means is again made available for another operation.

The operation of mechanism D of the connector switch shown in Fig. 2, and the common mechanism at the left of said figure is the same as in Fig. l with the exception that said mechanisms are not made available to another switch until switch B has returned to normal atthe termination of a call.

It is now believed that the following detailed description will enable those skilled in the art to fully understand the invention.

When a subscriber at substation 1 removes his receiver from its switchhook, a circuit is closed to operate a line switch or finder (not shown) to select a trunk leading to an idle selector switch A and upon engaging the terminals of said trunk a ground at said line or finder switch is applied to conductor 2 in a manner well known in the art. A holding circuit is then closed for release magnet 3 individual to the selector A, which circuit extends from grounded battery, winding of magnet 3 and conductor 2 to ground. Magnet 3 energizes and remains in this condition until the ground is removed from conductor 2 by the return of the line or finder switch to normal position. When magnet 3 energizes, a self-interrupting circuit is established for stepping magnet 4: extending from grounded battery, winding, armature and back contact of said magnet, right armature and back contact of test relay 5, side-switch passes over a row of terminals 11 until the terminal individual to the particular selector switch seized is found. When the brush engages terminal 11 to which the conductor 12 is connected, a circuit is established from test relay 5, extendingfrom grounded b'attery, winding of said relay, side-switch wiper 13 in position 1, brush 10, terminal 11, conductor 12, inner left armature and back contact of relay 6, outer front contact and armature of magnet 3 to ground. Relay 5 energizes and locks up through wiper 13 in positions 1 and 2 to ground at the inner left armature and front contact ofsaid relay. At its right armature relay 5 breaks the selfinterrupting circuit of magnet 61 and brings the plunger carrying frame 9 to a stop before the row of contact springs individual to the selector switch A. Energization of relay 5 also closes a circuit for plunger magnet 141 traceable from grounded battery, winding of said magnet, outer left armature and front contact of relay 5 to ground. Magnet 14 operates to move the frame 9, against the tension .ofthe springs 15, until the plungers carried by said frame engage their respective contact springs. At this time a circuit is closed for the line relay 16 common to the group of selector switches, similar to switch A, said circuit extending from grounded battery, right winding of relay 16,'plunger 17,.spring contact 18, lower side of the subscribers line, the apparatus of substation 1, the upper side of the subscribers line, contact spring 19, plunger 20 and left winding of relay '16 to ground. Relay 16 energizes and closes a circuit for slow-to-release relay 21, extending from grounded battery, wind ing of said relay, front contact and armature of relay 16 to ground. Engagement of plunger 39 with contact 38 closes an energizing circuit for relay 6 extending to ground through wiper 37 in position 1.

' Relay 6 then locks up through its right windselector. receive a series of impulses from substation 1 corresponding tothe first digit of theing, front contact and right armature to ground on the conductor 2. By attracting its outer left armature, relay 6 prevents the ex tension of the ground at the armature of magnet 3 to any other selector switch after wiper 4 has moved into position 2. \Viper 1 in position 2 of the side switch extends the starting conductor to the next idle switch C so the seizure of another selector and the energi'zation of its magnet 3 will close the" circuit of the motor magnet 4 of the switch C to causethe sameto hunt for the seized Switch Ais now in condition to wanted line.

Deenergi'zation of relay 16 in response to the'first impulse transmitted, establishes a circuit for slowto-rfelea'se relay 22, extending from grounded battery, winding of said .relay, front contact. and armature of relay 21 and 'back contactand armature of relay 16 to ground. Relay 22 energizes and, to gether with relay 21, remains in this condition during the transmission of a series of impulses. Energization of relay 22 establishes a circuit for escape magnet 23 extend ing from grounded battery, left winding of magnet 23 and front contact and inner armature of relay 22 to ground. Energization of magnet 23 at this time has no effect upon the side switch which it controls. In response to each deenergization of relay 16 due to the impulses transmitted, a circuitis also closed for primary stepping magnet 2a of switch A. extending from grounded battery, winding of said magnet, contact spring 25, plunger 26, side-switch wiper 27 in position 1, front contact and armature of relay 21 andbach contact and armature of relay 16 to ground. Magnet 24 operates to step brushes 28, 29 and 30 of switch A in p a group selecting movement.

At the termination of the series of impulses, relay 16 remain energizedand opens the circuit for slow-to-release relay 22 which, aftcran interval of time,releases. Deenergizatiotn of relay 22 opens the previously; described circuit for escape magnet 23 which releases and in so doing moves the side switch wipers into position 2. Another circuit is immediately established for escape magnet 23, extending from grounded battery, right winding of said magnet back contact and outer armature of relay 22, plunger 31, contact spring 32, primary offnormal contact 33' which closed upon the first step of the brushes of switch A, and secondary off-normal contact 34; to ground. Escape magnet 23. energizes in this circuit but in so doing does not affect the side switch wipers. When the side switch wipers l 05 move into position 2, a self-interrupting circuit is established for secondary stepping magnet 35, which circuit extends from grounded battery, winding, armature and back contact ofmagnet 35, contact spring 36, 7

plunger 80 and side switch-wiper 37 in position 2 to ground. Each energization of the magnet 35 operates to step the brushes 28, 29 and 30 over the terminals of the sclected group to hunt for an idle trunk there- 1 15 in. The first step of the brushes of switch 7 A in thetrunk hunting operation opens the by ground on the test terminals thereof.

Therefore, during. the passage of brushes of the, switch A, over terminals of busy switches, an energizing circuit for escape magnet 23 will be maintained through test brush 3O instead'of primary and secondary I off-normal contacts 33 and 341. When brush 30, engages a-terminal upon which there is no opening the self-interrupting circuit of secondary stepping magnet and the brushes 28, 29 and 30 of switch A come to rest on the terminals leading to an idle connector switch. Side switch'wiper 13, in moving from position 2 to position 3, opens the locking circuit for relay 5 which then releases and in so doing breaks at its outer left armature the circuit for magnet 14. De'elnergization of this magnet permits the returning of plunger carrying frame 9 to its normal position under the influence of the springs 15 ,and thus removes the several plungers from engagement with their respective contact springs. The return to normal of contact springs 18, 19 and 32 extends the subscribers line to the next succeeding switch. Release of relay 5 also closes a self-interrupting circuit for magnet 4 extending from grounded battery, winding, armature and back contact of said magnet, right armature and back contact of relay 5 and off-normal contact to ground, said contact having been closed when the previously described circuit for magnet 4 was established to rotate shaft 8. Magnet 4 now operates to return frame 9 and finder brush 10 to normal position, whereupon this apparatus will be in condition to extend another call.

If, during the operation of the switch A, and while the side switch wipers are in positions 2 or 3, the subscriber at substation 1 abandons the call by replacing his receiver upon its switchhook, the circuit for line relay 16 is opened and this relay releases its armature. In so doing, the circuit for slowto-release relay 21 is also opened but before this relay can retract its armature, a circuit is established for release magnet 41 extending from grounded battery, winding of said magnet, side-switch wiper 27 in position 2 or 3, front contact and armature of relay 21 and back contact and armature of relay 16 to ground. Release magnet 41 operates to return the side switch wipers to normal. Bemoval of ground from the conductor 2 by the return of the line or finder switch (not shown) causes the release of relay 6 and magnet 3 which then restores brushes 28, 29 and 30 to normal position. The switch is now ready for another operation.

Let it now: be assumed that brushes 28, 29 and 30 of switch A engage terminals of the trunk leading to connector switch B, as shown in Fig. 2. The ground upon the release conductor 2 is now extended through the brush 30 to conductor 42 of connector switch B which results in the energization of release magnet 43 thereof. By attracting its armature, the magnet 43 establishes a,

circuit for stepping magnet 44 extending from grounded battery, winding, armature and back contact of said magnet, right armature and back contact of test relay 45, side-switch wiper 45 in position 1, outer armature and back contact of relay 50, inner front contact and armature of magnet 43 to ground. Magnet 44 operates in the same manner as described in connection with magnet 4 to rotate shaft 46, the plunger carrying frame 47 and finder brush 48 until the latter engages the terminal 49 individual to the switch B. A circuit is'then closed for test relay 45 extending from grounded bat tery, right winding of said relay, brush 48, terminal 49, back contact and inner armature of relay 50, outer front contact and armature of relay 43 to ground. Energization of relay 45 opens, at its right armature, the circuit for magnet 44 which then ceases to operate and the plungers carried by frame 47 are positioned before the contact springs individual to switch B. The energization of relay 45 also closes an energizing circuit at its left armature and front contact for magnet 51 which operates to engage the several plungers carried by frame 47 with their respective spring contacts. A circuit is then closed for relay from battery through the windingof said relay, spring contact 52, plungers 53 and 54 and spring contact 55 to ground upon the release conductor 42. Relay 50 in attracting its inner armature, opens the original energizing circuit for relay 45 but this relay does not release due to a holding circuit extending from grounded battery, through the left winding of relay 45, plunger 54 and spring con- .tact 55 to ground on the conductor 42.

When the several plungers are engaged with their spring contacts, a circuit is also closed for line relay 56 extending from grounded battery, right winding of said relay, plunger 57, contact spring 58, the subscribers sub' station apparatus, contact spring 59, plunger 60 and left winding of relay 56 to ground. Relay 56 energizes and establishes a circuit for'slow-to-release relay 61 which,

in attracting its armature, prepares an energizing circuit for slowto-release relay 62. The switch is now in condition to receive sets of impulses transmitted from the calling subscribers substation to step brushes 63, 64 and 65 onto the terminals of the line individual to the called substation 66.

In response to the first dec'nergization of line relay 56 when the first set of impulses is transmitted, the previously mentioned circuit for slow-to-release relay 62 is closed and this relay in attracting its armature establishes an energizing circuit for escape magnet 67 extending from grounded battery, winding of said magnet, front contact and inner armature of relay 62 to ground. Magnet 67 energizes but does not at this time affect the side switch mechanism in so doing. Each deenergiz'ation of line relay magnet 68 extending from grounded battery, winding of said magnet, contact spring .69, plunger 70, side switch wiper 71 in position 1, front contact and armature of relay 61 and back contact and armature of relay 56 to ground. Magnet 68 operates in response to each impulse to step the brushes of switch B to the group of terminals containing those of the called line. At the termination of thisfirst series of impulses, line relay '56 remains energized and thus permanently opens the circuit for slow-to-release relay .62 which, after an interval, releases. Relay 62, in deenergizing, opens the circuit for escape magnet 67 and when this magnet releases the side-switch wipersare all moved to position 2. lVhen the side-switch wiper .45 moves into position 2 and each position thereafter, the same operates to extend another selector switch similar to switch D over a multiple of the common conductor 72. The side switch wiper 15. in moving into position-2 extends the starting conductor 72 to the next idle switch, so that when a connector is seized and its magnet 43 operated the groundapplied by the armature of this magnet is transmitted over side switch arm in positions 2, 3 and 4: to the stepping magnet 44 of such switch D. The subscriber at substation 1 then transmits another set of impulses corresponding to the last digit of the wanted line, and in response to each impulse line relay 56 is again deenergized to close the circuit of the secondary stepplng magnet 73 extendmg from grounded battery, winding of said magnet,

armature of relay 56 to ground. In respouse to the operation of secondary magnet will bedenoted by ground upon the test terminal 75 and as soon as brush engages 73, brushes: 63, 64 and 65 arestepped over the terminals of the selected group until those individual to the called substation 66 are reached. At the termination of the second set of impulses, line relay 56 remains energized and opens the energizing circuit for slow-to-release relay 62.

If the called line is busy, this condition said terminal a circuit will be established for test relay 76 extending from grounded battery, left winding of' said-relay, back contact and outer armature of relay 62,

-which'released after the energizing circuit therefor was opened by line relay 56, sideswitch wiper 77, plunger 5 contact spring 78, brush 65 and terminal7 5 to ground. It

will be noted that escape magnet 67 is made slow-to-release so that after the energizing circuit thereforis opened'by the release of relay 62, said magnet will not release before the energizing circuit for test relay 76 has been established, at which time another energizing circuit is maintained for magnet 67 extending to ground, through the inner left armature and front contact at said relay 76. The side-switch wipers will thus be prevented from moving out of position 2 to position 3. hen relay 76 is energized, the same is locked up through its right winding, front contact and armature to ground upon the conductor 41-2 through the plunger 54 and spring contact 55. By attracting its outer left armature, relay 76 applies a busy tone from the apparatus BZ to the calling line in a manner well known in the art and thecall ing subscriber, upon hearing this busy tone, replaces his receiver upon its switchhook. This will open the circuit for line relay 56 which in turn causes the release of relay 61. A circuit is then established for release magnet 79 extending from grounded battery, winding of said magnet, side switch wiper 80 in position 2, back contact and armature of relay 61 and back contact and armature of relay 56 to ground. Magnet 79 energizes and operates to restore the side switch deenergization of release magnet T3 indi-' vidual to switch B. The deene'igizationof magnet 4 -3 returns the brushes 63, 64 and 65 to normal. The holding circuit for relay 45 is also opened by the removal of ground from conductor 42, and relay 15, in releasing, removes ground from its left armature to deiinergize magnet 51 which, in so doing, retracts the several plungers from their re.- spective spring contacts. Relay 4:5, in releasing, also closes at its right armature a self-interrupting circuit for magnet 44: extending to ground through the oit-normal contact 81 which was closed upon the first step of wiper 18 from its normal position. Magnet 4A now operates to return the brush carrying frame 47 and wip'erAS to normal position. Upon reaching this position, oftnormalcontact 81 is opened andmagnet 14i ceases to operate, whereupon the switch is in condition to receive another call. Should the calling subscriber abandon the call while they switch is being operated, and the side switch-wiper 80 is in its second, third or fourth positions, the release of the switch will occur in the same manner as above described.

66 is idle when'the brushes (of connector switch B are engaged with the terminals of the called substation line, test relay 76 will remain inert and upon the release of relay 62, at the termination of the second series of impulses, escape magnet, 67 will 'deenergize and move the side-switch wipers to po- 'sition 3. Inthis position, ringingjcurrent will be applied to the called line over a circuit extending from the source of ringing current 82, back contact and armature of magnet 67, winding of relay 83, side-switch wiper 84: in position 3, plunger 57, contact spring 85, brush 64, terminal 86, subscribers substation 66 including the ringer apparatus thereat, terminal 87, brush 63, contact spring 88, plunger 60 and side-switch wiper 89 in position 3 to ground. This ringing current operates a signal at the called subscribers substation but is not sufficient to energize relay 83 through the winding of which said current passes. When the called subscriber removes the receiver from its switchhook, sufiicient current will pass through relay 83 to energize the same, and in attracting its armature, an energizing circuit is established for escape magnet 67 extending from grounded battery, winding of said magnet, side-switch wiper 90 in position 3 and armature and front contact of relay 83 to ground. Magnet 67 operates to move the side-switch wipers from position 3 to position 4, whereupon conversation between the calling and called subscribers may proceed, talking current for the called subscribers line being supplied in the usual manner by relay 91. The mechanical construction of the side switch whereby it moves its wipers into position 4: upon energization instead of denergization may be as shown in Fig. 9 of Patent 1,231,013, issued June 26, 1917, to Charles L. Goodrum and described in lines 89 to 102 of page 3 of said patent. At the termination of the conversation, the release of the switch is controlled in the same manner as above described when the calling subscriber replaces his receiver upon its switchhook.

Applicants are claiming in a copending application, Serial No. 315,828, filed August 7, 1919, a circuit arrangement wherein controlling equipments common to a greater number of switches are automatically preallotted so as to be temporarily available to a seized trunk to control the same.

What is claimed is:

1. In a telephone system, groups of selector switches, groups of connector switches, impulse relays for each group less in number than the switches thereof and common to such switches, and electromagnetic means automatically actuated upon the seizure of one of said switches for associating an idle impulse relay of the corresponding group with said switch to cooperate in the setting of the same.

2. In a telephone system, groups of selector switches, groups of connector switches,

impulse relays for each group less in number than the switches thereof and common to such switches, electromagnetic means automatically actuated upon the seizure of one of said switches for associating an idle impulse relay of the corresponding group with such switch to cooperate in the setting of the same, means for rendering the impulse relay used in setting the selector again accessible to other selectors of its group when said selector is set, and means for rendering the impulse relay used in setting the connector again accessible to other connectors of its group when the called party answers.

3. In a telephone system, groups of selector switches, groups of connector switches, impulse relays for each group less in number than the switches thereof and common to said switches, electromagnetic switches automatically actuated by the seizure of said switches for temporarily associating impulse relays from corresponding groups of impulse relays with such switches, and means whereby the electromagnetic switches and impulse relays revert to common use after the associated switches are set.

4:. In a telephone set, groups of selector switches, groups of connector switches, control equipments for each group comprising an impulse relay, a release magnet, slow relays and a side switch, these equipments being less in number than the switches of the group and being common thereto, elec tromagnetic means automatically actuated upon the seizure of one of said switches for associating an idle equipment of the corresponding group with such switch to cooperate in the setting thereof.

5. In a telephone system, groups of selector switches, groups of connector switches, control equipments for each group comprising a step-by-step switch, an impulse relay, a release magnet, slow relays and a side switch, these equipments being less in number than the switches of the group and being common thereto, and means for causing an idle one of said step-by-step switches to connect its equipment to a switch upon the seizure of such switch, and means whereby the control equipments revert tov common use after the corresponding switches are set.

6. In a telephone system, a subscribers line, groups of selector switches, groups of connector switches, impulse relays for each group less in number than the switches thereof and common to such switches, electromagnetic means automatically actuated upon the seizure of one of said switches for associating an idle impulse relay of the corresponding group with such switch to cooperate in the setting of said switch, and a dial associated with said subscribers line for actuating said impulse relays in succession.

In witness whereof we hereunto subscribe our names this 4th day of August, A. D.

JAMES L. MZGQUARRIE. CHARLES L. GOODRUM. 

